Table 1.

Characteristics of different degrees of TBI in different species.

Species
Human	Mild TBI (1) Any period of loss of consciousness up to 30 min (2) Posttraumatic amnesia not exceeding 24 h (3) Any period of confusion or disorientation (4) Transient neurological abnormalities (5) A GCS score of 13–15 (6) Normal structural imaging (7) Postconcussion symptoms may resolve during 12 weeks
	Moderate TBI (1) A possible loss of consciousness lasting up to a few hours (2) Confusion lasting from days to weeks (3) Physical, cognitive, and/or behavioral impairments lasting for months (1) Abnormal structural imaging (2) A GCS score of 9–12
	Severe TBI (1) Sustained loss of consciousness (>24 h) (2) Surviving patients exhibiting chronic physical and emotional disabilities (3) Abnormal structural imaging (4) A GCS score of less than 9
Mouse	Mild TBI (1) CCI: depth: 0.1–1.0 mm; velocity: 3.0–6.0 m/s (2) Tissue loss: lesions confined to the cortical layer (3) Cortical depression <0.5 mm, velocities <4.0 m/s
	Moderate TBI (1) CCI: depth: 0.5–3.0 mm; velocity: 1.5–6.0 m/s (2) Tissue loss: considerable cortical tissue loss with little to no overt hippocampal loss (3) Cortical depression 1.0–1.5 mm, velocities 4.0–5.0 m/s
	Severe TBI (1) CCI: depth: 0.5–2.0 mm; velocity: 3.0–6.0 m/s (2) Tissue loss: extensive overt hippocampal lesions along with cortical tissue loss (3) Cortical depression >2.0 mm, velocities >5.0 m/s

Note: TBI: traumatic brain injury; CCI: controlled cortical impact; GCS: the Glasgow Coma Scale.